AND/OR OR DRY MODE

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 61/808,608, filed April 4, 2013 and incorporates the same by reference as if set forth herein in its entirety.

STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF INVENTION

a. Field of Invention

The invention relates generally to the field of process fluid cooling. More particularly, the invention refers to a heat exchange systems and methods for selectively cooling process fluid in wet and/or dry mode.

b. Background of Invention

Current state of the Art

Cooling towers, understood as open heat exchange systems, are the most efficient means to reject heat from warm process fluid (most often water). They are used in many

applications such as power generation, food processing and HVAC. They are inherently efficient due to the direct transfer of heat from the process fluid stream that trickles down plastic tower fill to the outside air stream flowing up across the same media. Cooling towers reject heat from the warm process water by evaporating a portion of it (usually around 1% of total flow). A cooling tower can do about 2 ½ tons of cooling per square foot of tower fill where a fluid cooling can only do about 1 ½ tons per square foot (40% less).

Closed loop fluid coolers, understood as closed heat exchange systems, have been field installed either in series or in parallel flow with cooling towers to conserve on water during warmer outdoor operating temperatures. Closed loop fluid coolers reject heat from the warm process water indirectly to the outside air stream by transferring heat through the tube walls. Usually fluid cooler heat exchangers are made out of galvanized steel for corrosion purposes from constant exposure to the water spray. However, the galvanize coating is only on the outside. Therefore, circulating water from an open system which is continually aerated will quickly deteriorate the inside of the steel tubing. For this reason, stainless steel tubing coils or polymer tubing coils are required for fluid coolers operating in an open system where aerated water is passed through the inside of the tubing. It is desirable to have a heat exchange system that is capable of selective operation in wet mode (as a cooling tower), or in dry mode (as a fluid cooler). An operator can selectively switch the heat exchange system between modes depending on the desired cooling capacity, the ambient climate, plume mitigation, and / or water evaporation / consumption.

The tubes that make up the coils a of fluid cooler also can act as a surface area media, similar to plastic fill in a cooling tower. If water is sprayed over the tubes, additional evaporative heat exchange will transfer heat from the process fluid through the tube walls as the spray water is sprayed onto the tubes and evaporated. It is therefore desirable to have a heat exchange system wherein the process water can be directed first through the inside of the tubing as a closed loop fluid cooler and then again over the outside of the tubing through the water spray assembly giving the tubing the advantage of passing the process water through the system twice.

When a heat exchange system is operated in wet mode and mixed wet /dry mode, the air that is used for the evaporation process has dirt, pollen and trash in it and this gets washed out as it moves through the tower fill leaving the debris in the water which collects in the sump and can

be a maintenance problem by clogging spray nozzles and heat transfer tubes. It is therefore desirable to have a heat exchange system that integrally incorporates a debris filter as well as a means of flushing or cleaning the filter automatically with little or no operator intervention.

U.S. Pat. No. 3,994,995 discloses a wet/dry cooling tower with an upper tubular heat exchange section located over a lower sloped fill section. After partial cooling in the upper tubular section, liquid is either directed to the lower film fill section or bypasses it depending on cooling requirements.

Patent Publication U.S. Patent No. 4,076,771 discloses separate dry and wet discharge paths in a heat exchange cooling tower. US Patent No. 4,112,027 discloses a combined direct and indirect cooling apparatus and method. European Patent EP092246 discloses an operating method for a dry/wet cooling tower having a least partial water-side series connection of dry part and wet part.

SUMMARY OF INVENTION

One object of the invention is to provide a heat exchange system and method to selectively operate to cool process water in wet and/or dry mode. An object of the invention is to attain high cooling efficiencies of heat exchange systems while providing the flexibility of wet and/or dry operation using a minimal square footage footprint. An object the invention is to enable a heat exchange system and method to selectively operate to cool process water in wet and/or dry mode and also a plume abatement method and configuration. An object the invention is to enable a wet / dry heat exchange system that integrally incorporates a debris filter as well as a means of flushing or cleaning the filter automatically with little or no operator intervention.

The instant invention is directed to a heat exchange system adapted to selectively operate in wet mode, dry mode, or both wet and dry mode. The heat exchange system comprises an inlet pass array of tubing that extends from an inlet manifold end tank for a predetermined length to a transition end. A return communicates fluid from the transition end of the inlet pass array of tubing to a second pass array of tubing. The second pass array of tubing extends from the return at a first end for a predetermined length to a second end. The second pass array exists below the inlet pass array and defines a first partial envelopment that exists between the inlet pass array, the return, and the second pass array. A second return communicates fluid from the second end of the second pass array of tubing to a third pass array of tubing. The third pass array of tubing extends from the second return at a lead end for a predetermined length to a trailing end. The third pass array exists below the second pass array and defines a second partial envelopment that exists between the second pass array, the second return, and the third pass array. One or more subsequent pass arrays of tubing exist below and are in fluid communication with an above pass. The one or more subsequent pass arrays form a final pass array of tubing that communicates fluid to an outlet.

Water is the commonly used in open heat exchange systems. However, the term "fluid" is used herein interchangeably with water. Such interchangeable use not intended to limit the breadth of the invention.

To facilitate wet mode operation, one or more spray nozzles are located above an array of tubing and adapted to spray fluid onto the one or more arrays of tubing located below. At least one fluid router is configured to convey process fluid only into the arrays of tubing in dry mode, only to the spray nozzles in wet mode, or to both into the arrays of tubing and to the spray nozzles.

In dry mode, air is drawn over the tubes forming the arrays of tubing and through the partial envelopments while fluid is cooled as the fluid is selectively routed through the inside of the one or more arrays of tubing from the inlet manifold end tank to the outlet. In wet mode, air is drawn over the tubes forming the arrays of tubing and through the partial envelopments while fluid is selectively routed to the one or more spray nozzles onto the one or more arrays of tubing. In a mixed mode, the process water is routed into the arrays and to the spray nozzles.

The heat exchange system typically is fixed in a cabinet having a fan system for drawing air upward through the coil, wherein cooled water from the spray nozzles and / or the outlet dumps into a sump where it is collected and returned to the process heat load to remove heat from the process heat load and convey the process water back to the heat exchange system to complete the cycle.

In an alternate embodiment, a heat exchanger comprises a plurality of layers of tube arrays arranged in a stacked relationship such that fluid passes through each layer in a generally lateral manner, through a layer transition portion that conveys fluid to a lower layer of tube arrays existing at a lower elevation. A plurality of partial envelopments exist between two layers of the tube arrays and a layer transition portion. At least one partial envelopment exists above a layer of tube arrays and contains one or more nozzles for spraying liquid onto one or more layers of tube arrays and / or into one or more other partial envelopments located below. A fluid router selectively directs fluid sequentially into each tube of the plurality of layers and /or to the one or more nozzles. Wherein, process fluid is cooled by routing the fluid into the plurality of layers of tube arrays and / or routing the fluid to the one or more spray nozzles, and drawing air over a plurality of tube surfaces forming the plurality of layers.

In an embodiment of the present invention, a method of cooling a fluid comprises providing a heat exchange system capable of selective operation in wet mode or dry mode, said heat exchange system comprising a plurality of layers of tube arrays arranged in a stacked and/or serpentine relationship such that fluid passes through each layer in a generally lateral manner, through a layer transition portion that conveys fluid to a lower layer of tube arrays existing at a lower elevation, to an outlet. At least one partial envelopment exists above at least one of the plurality of layers and contains one or more nozzles for spraying liquid onto one or more layers of tube arrays and / or into one or more other partial envelopments formed between two layers of the plurality of layers. Air is drawn over a plurality of tubes forming one or more of the plurality of layers of tube arrays, and fluid is directed to a fluid router that functions to pass fluid (a) into the plurality of tubes forming the plurality of layers of tube arrays to an outlet, and / or (b) to the one or more nozzles.

Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the invention and together with the detailed description serve to explain the principles of the invention. In the drawings:

Fig. 1 is a partial schematic front view of an embodiment of the present invention heat exchange system;

Fig. 2 is a partial schematic front view of an embodiment of the present invention heat exchange system operating in dry mode;

Fig. 3 is a partial schematic front view of an embodiment of the present invention heat exchange system operating in wet mode;

Fig. 4 is a partial schematic perspective of an embodiment of the present invention heat exchange system operating in wet mode having an inlet side fluid router;

Fig. 5 is a partial perspective sectional view of an embodiment of the present invention array of tubing that forms a pass or layer;

Fig. 6 is a partial cross sectional view of an embodiment of the present invention array of tubing that forms a pass or layer;

Fig. 7 is a s a partial schematic perspective of an embodiment of the present invention inlet manifold end tank showing the access panel open and the debris filter; and

Fig. 8 is a s a partial schematic perspective of an embodiment of the present invention inlet manifold end tank showing the access panel closed;

Fig. 9a shows a partial cutaway schematic view of an inlet side fluid router in a first position according to an embodiment of the present invention;

Fig. 9b shows an isometric view of an inlet side fluid router in a first position according to an embodiment of the present invention;

Fig. 10a shows a partial cutaway schematic view of an inlet side fluid router in a second position according to an embodiment of the present invention;

Fig. 10b shows an isometric view of an inlet side fluid router in a second position according to an embodiment of the present invention;

Fig. 11a shows an isometric view of a valve body of an inlet side fluid router according to an embodiment of the present invention; Fig. 1 lb shows an isometric view of a valve body of an inlet side fluid router according to an embodiment of the present invention;

Fig. 11c shows an isometric view of a valve body of an inlet side fluid router according to an embodiment of the present invention;

Fig 12 shows a schematic view of the heat exchange system in dry mode according to an embodiment of the present invention;

Fig 13 shows a schematic view of the heat exchange system after transition from dry mode to wet mode according to an embodiment of the present invention; and

Fig 14 shows a schematic view of the heat exchange system in dry mode according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring now to the Figures in general, and specifically to Fig. 1 - Fig. 4, embodiments of the present invention are directed to a heat exchange system 11 adapted to selectively operate in wet mode, dry mode, or both wet and dry mode. The heat exchange system 11 comprises an inlet pass array 13 of tubing that extends from an inlet manifold end tank 15 for a predetermined length to a transition end 17. A return 19 communicates fluid from the transition end 17 of the inlet pass array 13 of tubing to a second pass array 21 of tubing. The second pass array 21 of tubing extends from the return 19 at a first end 23 for a predetermined length to a second end 25. The second pass array 21 exists below the inlet pass array 13 and defines a first partial envelopment 27 that exists between the inlet pass array 11, the return 19, and the second pass array 21. A second return 29 communicates fluid from the second end 25 of the second pass array 21 of tubing to a 31 third pass array of tubing. The third pass array 31 of tubing extends from the second return 29 at a lead end 33 for a predetermined length to a trailing end 35. The third pass array 31 exists below the second pass array 21 and defines a second partial envelopment 37 that exists between the second pass array 21, the second return 29, and the third pass array 31. One or more subsequent pass arrays 39 of tubing exist below and are in fluid communication with an above pass 13/21/31. The one or more subsequent pass arrays 39 form a final pass array 41 of tubing that communicates fluid to an outlet 43.

Referring briefly to Figs. 5-6, there is shown a plurality of individual tubes 51 that form a pass array 13/21/31/39. Many individual tubes 51a form each array 13/21/31/39.

To facilitate wet mode operation, one or more spray nozzles 45 are located above an array 13/21/31/39 of tubing and adapted to spray fluid onto the one or more arrays 13/21/31/39 of tubing located below. At least one fluid router 49 is configured to convey process fluid only into the arrays 13/21/31/39 of tubing in dry mode, only to the spray nozzles 45 in wet mode, or to both into the arrays 13/21/31/39 of tubing and to the spray nozzles 45.

In dry mode, air is drawn over the tubes 51 forming the arrays 13/21/31/39 of tubing and through the partial envelopments 27/37/47 while fluid is cooled as the fluid is selectively routed through the inside of the one or more arrays 13/21/31/39 of tubing from the inlet manifold end tank 15 to the outlet 43. In wet mode, air is drawn over the tubes 51 forming the arrays 13/21/31/39 of tubing and through the partial envelopments 27/37/47 while fluid is selectively routed to the one or more spray nozzles 45 onto the one or more arrays

13/21/31/39 of tubing. In mixed mode, the process water is routed into the arrays

13/21/31/39 and to the spray nozzles 45.

The heat exchange system 11 typically is fixed in a cabinet having a fan for drawing air upward through the arrays 13/21/31/39, wherein cooled water from the spray nozzles 45 and / or the outlet 43 dumps into a sump where it is collected and pumped to the process heat load to remove heat from the process heat load and convey the process water back to the heat exchange system 11 to complete the cycle.

In an embodiment of the present invention heat exchange system, the fluid router 49 includes an inlet side fluid router 49a located upstream of the inlet manifold end tank. The inlet side fluid router 49a is adapted to selectively route fluid (i.) [in dry mode] to the inlet manifold end tank 15 into the arrays 13/21/31/39 of tubing to the outlet 43 and / or (ii.) [in wet mode] to the one or more spray nozzles 45. The inlet side fluid router 49a may be two valves, or a 3 way valve, connected to a process water source, one feeding the arrays

13/21/31/39, and the other feeding the spray nozzles 45. A 3 way valve is preferred.

However, any such valve capable of performing the desired function will suffice. Additional embodiments of the inlet side fluid router 49a are discussed herein.

In a preferred embodiment of the present invention heat exchange system, the fluid router 49 includes an outlet side fluid router 49b located downstream of the outlet 43 of the arrays of tubing . The outlet side fluid router 49b is adapted to selectively route fluid from the outlet 43 to the one or more spray nozzles 45 and / or to a sump. The outlet side fluid router 49a may be two valves, or a 3 way valve, connected to the outlet, one the spray nozzles 45, and another draining to a sump or directed back to the process heat load. A 3 way valve is preferred. However, any such valve capable of performing the desired function will suffice. Additional embodiments of the inlet side fluid router 49a are discussed herein. In an alternate embodiment of the present invention heat exchange system 11 , the fluid router 49 directs fluid (i.) to the inlet manifold end tank 15 wherein the fluid passes into the arrays 13/21/31/39 of tubing to an outlet 43 and / or (ii.) [in wet mode] to the one or more spray nozzles 45. As such, process fluid can be routed from the arrays 13/21/31/39 of tubing at locations other than inlet side and outlet side. For example, at a second pass array 21 or subsequent pass array 39. Similar valve configurations may be used as discussed herein.

In a preferred embodiment of the present invention, the heat exchange system 11 further includes a high surface area media 53 contained within the one or more partial envelopments 27/37/47. The high surface area media 53 provides evaporative surface area to facilitate evaporative heat exchange when air and liquid are exposed over the media to cool fluid sprayed onto the one or more arrays of tubing and / or the media. Such high surface area media, or tower fill, is available from manufacturers including Brentwood Industries of Reading Pennsylvania.

In an embodiment of the present invention heat exchange system 11 , one or more of the inlet pass array 13, the second pass array 21, the third pass array 31, and the one or more subsequent pass arrays 39 are of a slab type configuration, which is definable by tube sheet manifolds existing on each end. The tube sheet manifolds provide for transition of the flow of fluid between a common supply conduit to a plurality of tubes 51 that form a pass array 13/21/31/39.

In an embodiment of the present invention heat exchange system 11 , the one or more arrays of tubing 13/21/31/39 are of a continuous coil configuration, which is defined such that each tube 5 la of the plurality of tubes 51 comprising the one or more arrays 13/21/31/39 of tubing extends continuously from the inlet manifold end tank 15, forming the one or more returns 19/29, to the outlet 43.

Referring to Figs. 7-8, in an embodiment of the present invention heat exchange system 11, the inlet manifold end tank 15 includes at least one wall 55 that transitions fluid flow between a common conduit 57 and a plurality of tubes 51 that form the inlet pass array 13.

In an embodiment of the present invention heat exchange system, the inlet manifold end tank 15 further includes a debris filter 59 existing between the common conduit 57 and the plurality of tube 51 that form the inlet pass array 13. The debris filter 59 traps debris in fluid conveyed into the inlet manifold end tank 15 from the common conduit 57 to prevent fouling of the tube arrays 13/21/31/39 of the heat exchange system 11. Preferably, an access panel 61 is formed into the at least one wall 55 to enable access to the debris filter 59 for inspection and cleaning. In an embodiment of the present invention heat exchange system 11 , the inlet pass array 13 of tubing is elevated at the transition end 17 relative to the inlet manifold end 15 tank for automatic cleaning of the debris filter 59 by enabling reversal flush of fluid by gravity flow from the inlet pass array 13 through the debris filter 59 to the common conduit 57. When a fluid router 49 closes supply fluid flow to the common conduit 57 and opens the common conduit 57 to a drain, a reversal of flow of fluid within the inlet pass array 13 is induced to cause a backwash of the fluid through the debris filter 59, to wash any debris from the filter 59 to the common conduit 57 and to the drain.

In a preferred embodiment of the present invention heat exchange system 11 , the inlet pass array 13 of tubing is located above the one or more spray nozzles 45 for aiding in the elimination of mist rising above the one or more spray nozzles 45 by heating said mist as it rises past the inlet pass array of tubing 13.

In an alternate embodiment of the present invention heat exchange system 11 , one or more arrays 13/21/31/39 of tubing are located above the one or more spray nozzles 45 for aiding in the elimination of mist rising above the one or more spray nozzles 45 by heating said mist as it rises past the one or more arrays 13/21/31/39 of tubing that are located above the one or more spray nozzles 45.

Alternately described, a heat exchanger 11 comprises a plurality of layers of tube arrays 13/21/31/39 are arranged in a stacked relationship such that fluid passes sequentially through each layer 13/21/31/39 in a generally lateral manner, through a layer transition portion 19/29/29a that conveys fluid to a lower layer of tube arrays 21/31/39 existing at a lower elevation. A partial envelopment 27/37/47 exists between two layers 13/21/31/39 of the tube arrays. At least one partial envelopment 27/37/47 exists above a layer of tube arrays 13/21/31/39 and contains one or more nozzles 45 for spraying liquid onto one or more layers of tube arrays 13/21/31/39 and / or into one or more other partial envelopments 27/37/47 that are located below the nozzles 45. A fluid router 49 selectively directs fluid into each tube 5 la of the plurality of layers 13/21/31/39 and /or to the one or more nozzles 45. Wherein, the heat exchanger enables the cooling of process fluid by routing the fluid into the plurality of layers of tube arrays 13/21/31/39 and / or routing the fluid to the one or more spray nozzles 45, and drawing air over a plurality of tube surfaces 63 forming the plurality of layers.

In an embodiment of the present invention, the heat exchanger 11 further includes a high surface area media 53 contained within one or more of the partial envelopments 27/37/47 The high surface area 53 media provides evaporative surface area when air and liquid are exposed onto the media 53 to cool fluid sprayed onto the one or more arrays of tubing 13/21/31/39 and / or the media 53.

In an embodiment of the present invention heat exchanger 11 , one or more of the plurality of layers 13/21/31/39 are of a slab type configuration definable by tube sheet manifolds existing on each end. The tube sheet manifolds provide for transition of the flow of fluid between a common conduit or end tank to a plurality of tube conduits that form a layer 13/21/31/39.

In an embodiment of the present invention heat exchanger 11 , the one or more of the plurality of layers of tube arrays 13/21/31/39 are of a continuous coil serpentine configuration defined such each tube 51a of a layer of tube arrays 13/21/31/39 extends continuously from an inlet 13, forming the layer transition portion 19 and one or more additional layers of tube arrays 21/31/39 and additional and transition portions 29/29a, to the outlet 43.

In an embodiment of the present invention heat exchanger 11 , the inlet includes an inlet manifold end tank 15 having the features discussed above.

In an embodiment of the present invention heat exchanger 11 , an inlet pass array of tubing 13 is elevated at the transition end 17 relative to the inlet manifold end 15 tank for automatic cleaning of the debris filter 59 by enabling reversal flush of fluid by gravity flow from the inlet pass array 13 through the debris filter 59 to the common conduit 57. When a fluid router 49 closes supply fluid flow to the common conduit 57 and opens the common conduit 57 to a drain, a reversal of flow of fluid within the inlet pass array 13 is induced to cause a backwash of the fluid through the debris filter 59, to wash any debris from the filter 59 to the common conduit 57 and to the drain.

In an embodiment of the present invention heat exchanger, the inlet pass array 13 of tubing is located above the one or more spray nozzles 45 for aiding in the elimination of mist rising above the one or more spray nozzles 45 by heating said mist as it rises past the inlet pass array 13 of tubing.

In an alternate embodiment of the present invention heat exchanger 11 , one or more layers of tube arrays 13/21/31/39 are located above the one or more spray nozzles 45 for aiding in the elimination of mist rising above the one or more spray nozzles 45 by heating said mist as it rises past the one or more layers of tube arrays 13/21/31/39 that are located above the one or more spray nozzles 45.

The invention further includes a method of cooling a fluid. A heat exchange system 11 capable of selective operation in wet mode or dry mode is provided. The heat exchange system 11 is as described herein. Air is drawn over a plurality of tubes 51a forming one or more of the plurality of layers of tube arrays 13/21/31/39, and air is further drawn through one or more partial envelopments 27/37/47. Fluid is directed to a fluid router 49/49a/49b that functions to pass fluid (a) into the plurality of tubes forming the plurality of layers of tube arrays to an outlet, and / or (b) to the one or more nozzles.

In an embodiment of the present invention, the step of "directing fluid to a fluid router" includes conveying fluid from a process fluid source into the plurality of tubes 51 forming the plurality of layers 13/21/31/39 to an outlet 43. At least one outlet router 49b is located at the outlet 43 selectively passes the fluid from the outlet 43 to the one or more nozzles 45, or passes the fluid from the outlet 43 to a sump.

Referring to Figs. 9-14 specifically, and all Figures generally, in an embodiment of the present invention, the step of "directing fluid to a fluid router" includes providing an inlet side fluid router 49a. The inlet side fluid router 49a is located upstream of the plurality of layers of tube arrays 13/21/31/39.

In a preferred embodiment the inlet side fluid router 49a includes a tube shaped housing 65 adapted to receive a valve body 67. The tube shaped housing 65 includes the following structural features:

(i) a process fluid source port 69 for receiving process fluid conveyed from a source,

(ii) a tubing port 71 for communicating process fluid to the plurality of layers of tube arrays 13/21/31/39 via the common conduit 57 of the inlet manifold end tank 15,

(iii) a spray port 73 for communicating process fluid to the one or more nozzles 45, and

(iv) a signal pressure port 75 for communicating a signal pressure from a signal fluid source to the valve body 67,

(v) a drain outlet port 77 for communicating backwashed process fluid to a drain via the common conduit 57 of the inlet manifold end tank 15.

In a preferred embodiment, the valve body 67 includes the following structural features:

(i) a signal pressure reading surface 79 opposing a process fluid pressure reading surface 81 to enable sliding of the valve body 67 within the tube shaped housing 65 from a first position to a second position depending upon the presence of the signal pressure exerted at the signal pressure port 75 relative to a process fluid pressure exerted at the process fluid source port 81 ,

(ii) a first bore or pathway 83 that communicates process fluid from the process fluid source port 69 to the spray port 73 when the valve body 67 is in the first position,

(iii) a second bore or pathway 85 that communicates process fluid from the process fluid source port 69 to the tubing port 71 when the valve body 67 is in the second position, and (iv) a third bore or pathway 87 that communicates backwash process fluid from the tubing 71 port to the drain outlet port 77 when the valve body is in the first position, allowing the flush of any debris from the debris filter 59 to the drain when the inlet pass array of tubing 13 is elevated at the transition end 17 relative to the inlet manifold end tank 15,

(v) a signal pressure bleedoff bore or pathway 89 that communicates signal fluid from the a signal pressure reading surface 79 to the first bore 83 and /or the second bore 85 to enable the valve body 67 to return to the second position when the signal pressure is shut off.

In operation, process fluid is pumped from a process fluid heat source to the process fluid source port 69 of the inlet side fluid router 49a. A signal fluid source controlled by a remotely located operator valve is in communication with the signal pressure port 75 of the inlet side fluid router 49a. In a preferred embodiment, the signal fluid source is city water or water used as makeup water that is supplied at domestic pressure rates in the 60-100psi range, although lower pressure domestic water may also suffice. The city water is isolatable from the inlet side router 49a with the operator valve. Preferably, the operator valve is a ball valve or the like that is hand operated. However, automatic valve operation can be incorporated to actuate the operator valve.

One purpose of the operator valve controlling the pressure at the signal pressure port 75 is to enable remote actuation of the valve body 67. Heat exchange systems are located on rooftops. Rather than have an operator climb to the eat exchange system 11 on the roof, the method provides for the valve to be located remote from the heat exchange system 11 , at allocation of easy access to an operator. Similarly, electromechanical means to route the process fluid are subject to maintenance and also isolation of electrical systems. By opening the operator valve, the city water pressure is communicated to the signal pressure port 75. This high pressure at the signal port 75 relative to the lower pressure pumped to the process fluid source port 69 causes the valve body to slide from the second position (dry mode shown in Figs. 10a and 10b) to the first position (wet mode shown in Figs. 9a and 9b).

Referring to Figs. 9a and 9b, 11a -11c, and 14, when the valve body 67 is in the wet mode or second position, the first bore or pathway 83 communicates the process fluid from the process fluid source port 69 to the spray port 73.

Referring to Figs. 10a and 10b, 11a -11c, and 12, when the operator valve is closed, the valve body 67 of the inlet side fluid router 49a travels to the second position. The second position enables the communication of process fluid from the process fluid source port 69 to the tubing port 71, via the second bore or pathway 85, enabling dry mode operation. Referring to Figs. 9a and 9b, 11a -11c, and 13, when the operator valve is again opened, the valve body 67 of the inlet side fluid router 48a travels to the first position (Figs. 9a-9b) allowing the communication of process fluid to the nozzles 45 transitioning from dry mode to wet mode. Also, the third bore or pathway 87 communicates backwash process fluid from the tubing 71 port to the drain outlet port 77 via the common conduit of the inlet manifold end tank. This allows the flush of any debris from the debris filter 59 to the drain when the inlet pass array of tubing 13 is elevated at the transition end 17 relative to the inlet manifold end tank 15. (Fig. 13)

Although particular embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those particular embodiments, and that various changes and modifications, including the omission of steps or the interchangeability of the order of steps, may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.